To provide a length adjustable strut of a kind described above to provide improved safety in accidental separation of an axial bearing from the bottom plate of the stand pipe of a strut.

A length adjustable strut for a chair or the like includes a stand pipe having a longitudinal axis A and a cylinder piston unit guided movably in a direction of a longitudinal axis. The end part in a longitudinal direction of the cylinder piston unit is fixed at a bottom plate 12a of the stand pipe by a longitudinal bearing 22. Against this, the axial bearing is firmly connected in a direction K of an axis A to the end part in a longitudinal direction of the cylinder piston unit 14 and further, the axial bearing 22 is provided with a fixed arm 42 to fix the axial bearing at the bottom plate of the stand pipe and a fixed bolt 44. In this case, the fixed bolt 44 is capable of being inserted through the cylinder piston unit into a space between the fixed arms 42 during axial fixed connection between the axial bearing 22 and the stand pipe bottom part 12a.